java - 如何使用标准 Java 布局管理器更正/居中 GridLayout？

Question

下面的代码代表了问题。由于我设置了北面板和南面板的高度，其余部分使用 GridLayout 转到中心面板。我认为，由于它不能在其行之间平均共享剩余像素，所以它只会留下它们。因此在下面的代码中，我们在南面板上有难看的白线。

我的问题是:如何确保当 GridLayout 没有占用整个空间时它至少居中？

通常我会使用 TableLayout 并对情况进行排序，但由于我正在写一个答案，所以我只想使用标准管理器。提前致谢，知道这一点对我非常有用。

例子:

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridLayout;
import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class AligningButonsTest
{
    public static void main(String[] args)
    {
        SwingUtilities.invokeLater(new Runnable()
        {
            @Override
            public void run()
            {                   
                JFrame f = new JFrame();
                f.setSize(800, 600);
                double CONSTANT_FACTOR = .1;
                int noOfRows = 5;
                JPanel centerP = new JPanel(new GridLayout(noOfRows,1));

                for(int i = 0; i < noOfRows; i++)
                {   
                    BoxPanel bP = new BoxPanel();
                    centerP.add(bP);
                }
                JPanel contentPane = new JPanel(new BorderLayout());                
                f.setContentPane(contentPane);
                contentPane.add(centerP, BorderLayout.CENTER);
                JPanel southP = new JPanel();
                southP.setBackground(Color.RED.darker());//southP.setOpaque(false);
                southP.setPreferredSize(new Dimension(1, (int)(CONSTANT_FACTOR* f.getHeight())));
                contentPane.add(southP, BorderLayout.SOUTH);
                JPanel northP = new JPanel();
                northP.setBackground(Color.RED.darker());//northP.setOpaque(false);
                northP.setPreferredSize(new Dimension(1, (int)(CONSTANT_FACTOR* f.getHeight())));
                contentPane.add(northP, BorderLayout.NORTH);            
                f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                f.setVisible(true);
            }
        });
    }   
}

class BoxPanel extends JPanel
{
    public BoxPanel()
    {
        setBorder(BorderFactory.createMatteBorder(1, 0, 1, 0, Color.RED));
        setBackground(Color.DARK_GRAY);
    }   
}

Answer 1

How to make sure that when the GridLayout is not taking the whole space it is at least centered?

JPanel wrapper = new JPanel( new GridBagLayout() );
wrapper.add( centerP );
contentPane.add(wrapper, BorderLayout.CENTER);  
//contentPane.add(centerP, BorderLayout.CENTER);